This project was undertaken to develop methods for application to neuroscience of x-ray microprobe and electron energyy loss spectroscopy coupled to high resolution scanning-transmission electron microscopy. These novel techniques provide very sensitive information on elements within spcific subcellular compartments. These topics were investigated in the current year: (1) qualitative localization of the neuroactive elements lead, manganese, and lithium, (2) quantitative studies on neuronal calcium metabolism; and (3) identification of fluorine-tagged neurotransmitter compartmentation.